Question 1

Which of these actions does the brain do during fasting or starvation?
A)It converts endogenous fatty acids into β-hydroxybutyrate.
B)It utilizes β-hydroxybutyrate from the blood stream.
C)It utilizes amino acids for fuel from degradation of brain protein.
D)It utilizes its glycogen stores as a first responding source of fuel.

Accepted Answer

During fasting or starvation, the brain adapts by utilizing β-hydroxybutyrate from the bloodstream, which is a ketone body produced by the liver from fatty acids. This process is a key adaptation to provide energy to the brain when glucose is scarce.

Question 2

What process is coupled to metabolism reactions and determines overall thermodynamic efficiency?
A)NADH oxidation
B)CO₂ release
C)ATP hydrolysis and synthesis
D)reduction of O₂

Accepted Answer

ATP hydrolysis and synthesis is coupled to metabolism reactions and determines overall thermodynamic efficiency. ATP hydrolysis releases energy, which drives cellular reactions, and ATP synthesis allows cells to store energy for later use. The efficiency of this process is determined by the amount of ATP produced per molecule of substrate consumed.

Question 3

What is the term for the constant availability of fuels in the blood,and what is the order of preference for fuel usage?
A)phosphorylation potential;glycogen > triacylglycerols > protein
B)fuel dynamics;triacylglycerols > glycogen > protein
C)metabolic regulation;triacylglycerols > glycogen > protein
D)caloric homeostasis;glycogen > triacylglycerols > protein

Accepted Answer

Caloric homeostasis refers to the constant availability of fuels in the blood, and the order of preference for fuel usage is glycogen, then triacylglycerols, and finally protein.

Question 4

Which of the following is NOT a characteristic of the energy charge (E.C.)of a cell?
A)It is rapidly changed by adenylate kinase.
B)E.C.has a range of 0-1.0.
C)It is a ratio of adenylate phosphoric anhydride bonds to total adenylate concentration.
D)It is 1.0 when all the adenylate is ATP.

Accepted Answer

All the other options are characteristics of the energy charge (E.C.) of a cell. The E.C. has a range of 0-1.0, and it is a ratio of adenylate phosphoric anhydride bonds to total adenylate concentration. It is also 1.0 when all the adenylate is ATP. However, the E.C. is not rapidly changed by adenylate kinase but rather reflects the balance between ATP synthesis and utilization in the cell.

Question 5

Muscle contractions occur when a motor nerve impulse causes Ca²⁺ release from specialized compartments.To which regulatory protein does Ca²⁺ bind to initiate events that result in sliding of myosin thick filaments along actin thin filaments? A)myoglobin B)calmodulin C)troponin C D)Na⁺/K⁺ ATPase

Accepted Answer

Ca²⁺ binds to troponin C, which in turn causes a conformational change in tropomyosin, exposing the myosin binding sites on actin and allowing for muscle contraction to occur. Myoglobin is a protein that stores oxygen in muscle tissue and is not directly involved in muscle contraction. Calmodulin is a regulatory protein that binds Ca²⁺ in other cellular processes, but not in muscle contraction. Na⁺/K⁺ ATPase is a sodium-potassium pump that maintains resting membrane potential, but is not involved in muscle contraction.

Question 6

What are the 2 metabolic roles served by ATP? A)promoting increased reaction speed and dephosphorylation B)changing both K_m and V_max C)allosteric regulation and stoichiometric involvement D)preventing futile cycles and changing K_m

Accepted Answer

ATP serves as an allosteric regulator in metabolic pathways and is involved stoichiometrically in reactions as a substrate or product.

Question 7

An energy charge (E.C.)of 0.9 is roughly 80% ATP,17% ADP,and 3% AMP.At this E.C.,which enzyme activities are low and which enzyme activities higher,respectively?
A)R;U
B)R;S
C)U;R
D)U;S

Accepted Answer

At an energy charge of 0.9, the activities of enzymes that utilize ATP as a substrate will be high, while the activities of enzymes that produce ATP will be low.

Question 8

Which of the following is NOT a characteristic of brain tissue?
A)Brain tissue is 20% or so of body mass.
B)Twenty percent of oxygen is consumed by the brain.
C)Oxygen consumption is independent of mental activity.
D)Brain tissue has no significant fuel reserves.

Accepted Answer

A) Brain tissue constitutes about 2% of body mass, not 20%. The other statements are accurate descriptions of brain tissue characteristics.

Question 9

Which of these enzymes is activated upon phosphorylation by AMP-activated protein kinase?
A)acetyl-CoA carboxylase
B)phosphofructokinase-2
C)glycogen synthase
D)3-hydroxy-3-methylglutaryl-CoA reductase

Accepted Answer

The answer of Which of these enzymes is activated upon...

Question 10

Which 2 molecules are unique in that they are the only compounds whose purpose is to couple the energy-yielding processes of catabolism to the energy-consuming reactions of anabolism?
A)NADH and ATP
B)ATP and [FADH₂]
C)[FADH₂] and NADH
D)ATP and NADPH

Accepted Answer

ATP and NADPH are unique because ATP provides energy for anabolic reactions, while NADPH provides reducing power, both essential for biosynthetic processes.

Question 11

Which of these enzymes catalyzes the reaction ATP + AMP → 2 ADP?
A)adenylate phosphorylase
B)AMP-phosphotransferase
C)ADP mutase
D)adenylate kinase

Accepted Answer

Adenylate kinase catalyzes the reaction ATP + AMP → 2 ADP.

Question 12

Which molecules are fed into catabolism to generate the metabolic intermediates needed to supply anabolism in photoautotrophs?
A)lipids
B)proteins
C)carbohydrates
D)nucleic acids

Accepted Answer

Carbohydrates are the main molecules fed into catabolism to generate the metabolic intermediates needed to supply anabolism in photoautotrophs. Specifically, glucose produced by photosynthesis is broken down through cellular respiration to produce ATP and other metabolic intermediates required for anabolic pathways like the synthesis of sugars, amino acids, and nucleotides. While lipids and proteins can also be catabolized to generate energy and metabolic intermediates, carbohydrates are the primary source in photoautotrophs. Nucleic acids are not typically catabolized for this purpose.

Question 13

Which of the following is NOT paired with their preferred substrate?
A)brain: glucose
B)heart: fatty acids
C)resting skeletal muscle: glucose
D)adipose tissue: fatty acids

Accepted Answer

Resting skeletal muscle primarily uses fatty acids as its preferred substrate for energy, not glucose. Glucose is more often utilized by skeletal muscle during periods of high-intensity exercise when the demand for quick energy is higher.

Question 14

Which of the following is a feature of ATP stoichiometry in metabolic pathways?
A)It is not a consequence of evolution.
B)A singular number is not required.
C)It results from biological adaptation.
D)It cannot be predicted from any chemical considerations.

Accepted Answer

The answer of Which of the following is a feature...

Question 15

What is the approximate energy charge of healthy living cells?
A)0.85-0.88
B)0.75-0.85
C)0.65-0.75
D)0.60-0.65

Accepted Answer

The energy charge of healthy living cells is typically in the range of 0.85 to 0.88, reflecting a high level of metabolic activity and energy availability.

Question 16

Which regulatory enzyme shows greater activity at low energy charge in an energy-producing pathway?
A)hemoglobin
B)phospholipase C
C)PKA
D)PFK-1

Accepted Answer

PFK-1 (phosphofructokinase-1) is a key regulatory enzyme in the glycolysis pathway that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. PFK-1 is allosterically activated by AMP and inhibited by ATP, making it responsive to changes in cellular energy charge. At low energy charge, there is a relatively high concentration of AMP, which allosterically activates PFK-1, thereby enhancing the rate of glycolysis to generate more ATP. Hence, choice D is the correct answer. Hemoglobin is a protein involved in oxygen transport and has no role in energy-producing pathways. Phospholipase C is involved in signal transduction pathways, and PKA (protein kinase A) is an enzyme that phosphorylates target proteins in response to intracellular cAMP levels. Although they are involved in cellular signaling, they do not play a direct role in energy-producing pathways.

Question 17

Which nucleotides are the principal energy source for protein,phospholipid,and polysaccharide synthesis,respectively?
A)UTP;GTP;CTP
B)GTP;CTP;UTP
C)CTP;UTP;GTP
D)UTP;CTP;GTP

Accepted Answer

GTP (guanosine triphosphate) is the principal energy source for protein synthesis, CTP (cytidine triphosphate) is the principal energy source for phospholipid synthesis, and UTP (uridine triphosphate) is the principal energy source for polysaccharide synthesis. Therefore, option B contains the correct order of nucleotides for each synthesis process.

Question 18

The brain prefers to use glucose as fuel.What does it use as it adapts to prolonged fasting or starvation?
A)glucose
B)β-hydroxybutyrate
C)fatty acids
D)amino acids

Accepted Answer

During prolonged fasting or starvation, the brain adapts to use ketone bodies as a fuel source, and β-hydroxybutyrate is a major type of ketone body produced by the liver from fatty acids.

Question 19

Which of the following metabolic pathways is strictly anabolic?
A)glycolysis
B)gluconeogenesis
C)citric acid cycle
D)pentose phosphate cycle

Accepted Answer

Gluconeogenesis is strictly an anabolic pathway because it involves the synthesis of glucose from non-carbohydrate precursors, essentially building larger molecules from smaller ones.

Question 20

Which of the following is NOT a major component of anabolic pathways?
A)NADH
B)glycolysis and citric acid cycle intermediates
C)ATP,GTP,CTP,UTP
D)NADPH

Accepted Answer

NADH is actually a major component of catabolic pathways (such as cellular respiration), not anabolic pathways. Anabolic pathways primarily utilize ATP, GTP, CTP, UTP, and NADPH, as well as intermediates from glycolysis and the citric acid cycle.

Quiz 33: Metabolic Integration and Organ Specialization

Which of these actions does the brain do during fasting or starvation?

What process is coupled to metabolism reactions and determines overall thermodynamic efficiency?

What is the term for the constant availability of fuels in the blood,and what is the order of preference for fuel usage?

Which of the following is NOT a characteristic of the energy charge (E.C.) of a cell?

Muscle contractions occur when a motor nerve impulse causes Ca²⁺ release from specialized compartments.To which regulatory protein does Ca²⁺ bind to initiate events that result in sliding of myosin thick filaments along actin thin filaments?

What are the 2 metabolic roles served by ATP?

An energy charge (E.C.) of 0.9 is roughly 80% ATP,17% ADP,and 3% AMP.At this E.C.,which enzyme activities are low and which enzyme activities higher,respectively?

Which of the following is NOT a characteristic of brain tissue?

Which of these enzymes is activated upon phosphorylation by AMP-activated protein kinase?

Which 2 molecules are unique in that they are the only compounds whose purpose is to couple the energy-yielding processes of catabolism to the energy-consuming reactions of anabolism?

Which of these enzymes catalyzes the reaction ATP + AMP → 2 ADP?

Which molecules are fed into catabolism to generate the metabolic intermediates needed to supply anabolism in photoautotrophs?

Which of the following is NOT paired with their preferred substrate?

Which of the following is a feature of ATP stoichiometry in metabolic pathways?

What is the approximate energy charge of healthy living cells?

Which regulatory enzyme shows greater activity at low energy charge in an energy-producing pathway?

Which nucleotides are the principal energy source for protein,phospholipid,and polysaccharide synthesis,respectively?

The brain prefers to use glucose as fuel.What does it use as it adapts to prolonged fasting or starvation?

Which of the following metabolic pathways is strictly anabolic?

Which of the following is NOT a major component of anabolic pathways?